S1W1 Obesity and Energy Balance part 5

Question 1

How was the effect of genetics on obesity proven before recent technology?

Answer 1

• studies comparing the BMI of identical twins, non-identical twins and siblings
• Psychiatrist in America called Albert Stunkard, did a study looking at the BMI of individuals who were adopted very early on in life, and found a strong relationship between the BMI of these individuals and their biological parents suggesting a strong genetic effect

Question 2

What is monogenic obesity?

Answer 2

• a very severe defect in a single gene has a very early, potent impact on obesity risk
• mostly related to appetite regulation
• common obesity isn’t due to monogenic causes

Question 3

What is polygenic obesity?

Answer 3

• where multiple genes with subtle effects combine to increase liklehood of being overweight
• More than 200 single nucleotide polymorphisms (differences in base pairs) linked to adiposity in different ways
• FTO gene has the most potent impact on BMI - if you have the risk alleles (version) of the FTO gene, you’re likely to be 2-3kg heavier than someone who doesn’t have those risk genes - the most potent single nucleotide polymorphism that we know of

Question 4

How do we know the environment also has an impact on obesity?

Answer 4

the human genome hasn’t changed in 70 years and obesity has risen to can’t all be down to genetics

Question 5

How does our environment impact obesity?

Answer 5

• Industrialisation, mechanisation, transport, leisure, work, diet
• Mechanisation - more modern labour saving devices
• Leisure time activities have changed - more sedentary time on computers, TV, smart phones, games consoles etc
• our genetic constitution is unsuited to 21st century living - we have a biology/physiology where we like to eat and store energy for when food isn’t available, but in todays environment there aren’t those periods with a lack of food available
• ‘normal response to an abnormal environment’
• Obesity is a ‘mis-match’ disease

Question 6

How do our genes influence our behaviour?

Answer 6

• your genes influence your choices
• office coffee morning scenario (Giles Yeo, 2021, Life Scientific Podcast)
  
  • A group of people are sat down in a meeting room drink tea and coffee
    
    • Somebody walks in with a plate of pastries and biscuits
    • Four types of people. . .
      
      1. The person who doesn’t even notice
      2. The person who notices, thinks twice, but stays put
      3. The person who has one biscuit
      4. The person who eats four biscuits without even realising
         These sorts of decisions happen multiple times a day, showing how genes can influences choices and contribute to obesity